1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * linux/arch/arm/mm/mmap.c
4 */
5 #include <linux/fs.h>
6 #include <linux/mm.h>
7 #include <linux/mman.h>
8 #include <linux/shm.h>
9 #include <linux/sched/signal.h>
10 #include <linux/sched/mm.h>
11 #include <linux/io.h>
12 #include <linux/personality.h>
13 #include <linux/random.h>
14 #include <asm/cachetype.h>
15
16 #define COLOUR_ALIGN(addr,pgoff) \
17 ((((addr)+SHMLBA-1)&~(SHMLBA-1)) + \
18 (((pgoff)<<PAGE_SHIFT) & (SHMLBA-1)))
19
20 /*
21 * We need to ensure that shared mappings are correctly aligned to
22 * avoid aliasing issues with VIPT caches. We need to ensure that
23 * a specific page of an object is always mapped at a multiple of
24 * SHMLBA bytes.
25 *
26 * We unconditionally provide this function for all cases, however
27 * in the VIVT case, we optimise out the alignment rules.
28 */
29 unsigned long
30 arch_get_unmapped_area(struct file *filp, unsigned long addr,
31 unsigned long len, unsigned long pgoff, unsigned long flags)
32 {
33 struct mm_struct *mm = current->mm;
34 struct vm_area_struct *vma;
35 int do_align = 0;
36 int aliasing = cache_is_vipt_aliasing();
37 struct vm_unmapped_area_info info = {};
38
39 /*
40 * We only need to do colour alignment if either the I or D
41 * caches alias.
42 */
43 if (aliasing)
44 do_align = filp || (flags & MAP_SHARED);
45
46 /*
47 * We enforce the MAP_FIXED case.
48 */
49 if (flags & MAP_FIXED) {
50 if (aliasing && flags & MAP_SHARED &&
51 (addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1))
52 return -EINVAL;
53 return addr;
54 }
55
56 if (len > TASK_SIZE)
57 return -ENOMEM;
58
59 if (addr) {
60 if (do_align)
61 addr = COLOUR_ALIGN(addr, pgoff);
62 else
63 addr = PAGE_ALIGN(addr);
64
65 vma = find_vma(mm, addr);
66 if (TASK_SIZE - len >= addr &&
67 (!vma || addr + len <= vm_start_gap(vma)))
68 return addr;
69 }
70
71 info.length = len;
72 info.low_limit = mm->mmap_base;
73 info.high_limit = TASK_SIZE;
74 info.align_mask = do_align ? (PAGE_MASK & (SHMLBA - 1)) : 0;
75 info.align_offset = pgoff << PAGE_SHIFT;
76 return vm_unmapped_area(&info);
77 }
78
79 unsigned long
80 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
81 const unsigned long len, const unsigned long pgoff,
82 const unsigned long flags)
83 {
84 struct vm_area_struct *vma;
85 struct mm_struct *mm = current->mm;
86 unsigned long addr = addr0;
87 int do_align = 0;
88 int aliasing = cache_is_vipt_aliasing();
89 struct vm_unmapped_area_info info = {};
90
91 /*
92 * We only need to do colour alignment if either the I or D
93 * caches alias.
94 */
95 if (aliasing)
96 do_align = filp || (flags & MAP_SHARED);
97
98 /* requested length too big for entire address space */
99 if (len > TASK_SIZE)
100 return -ENOMEM;
101
102 if (flags & MAP_FIXED) {
103 if (aliasing && flags & MAP_SHARED &&
104 (addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1))
105 return -EINVAL;
106 return addr;
107 }
108
109 /* requesting a specific address */
110 if (addr) {
111 if (do_align)
112 addr = COLOUR_ALIGN(addr, pgoff);
113 else
114 addr = PAGE_ALIGN(addr);
115 vma = find_vma(mm, addr);
116 if (TASK_SIZE - len >= addr &&
117 (!vma || addr + len <= vm_start_gap(vma)))
118 return addr;
119 }
120
121 info.flags = VM_UNMAPPED_AREA_TOPDOWN;
122 info.length = len;
123 info.low_limit = FIRST_USER_ADDRESS;
124 info.high_limit = mm->mmap_base;
125 info.align_mask = do_align ? (PAGE_MASK & (SHMLBA - 1)) : 0;
126 info.align_offset = pgoff << PAGE_SHIFT;
127 addr = vm_unmapped_area(&info);
128
129 /*
130 * A failed mmap() very likely causes application failure,
131 * so fall back to the bottom-up function here. This scenario
132 * can happen with large stack limits and large mmap()
133 * allocations.
134 */
135 if (addr & ~PAGE_MASK) {
136 VM_BUG_ON(addr != -ENOMEM);
137 info.flags = 0;
138 info.low_limit = mm->mmap_base;
139 info.high_limit = TASK_SIZE;
140 addr = vm_unmapped_area(&info);
141 }
142
143 return addr;
144 }
145
146 /*
147 * You really shouldn't be using read() or write() on /dev/mem. This
148 * might go away in the future.
149 */
150 int valid_phys_addr_range(phys_addr_t addr, size_t size)
151 {
152 if (addr < PHYS_OFFSET)
153 return 0;
154 if (addr + size > __pa(high_memory - 1) + 1)
155 return 0;
156
157 return 1;
158 }
159
160 /*
161 * Do not allow /dev/mem mappings beyond the supported physical range.
162 */
163 int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
164 {
165 return (pfn + (size >> PAGE_SHIFT)) <= (1 + (PHYS_MASK >> PAGE_SHIFT));
166 }
167
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